Nightmare bacteria resistant to most antibiotics are spreading across the US, according to the Centers for Disease Control and Prevention (CDC).

Health departments working with CDC’s Antibiotic Resistance (AR) Lab Network found more than 220 cases of unusual antibiotic-resistant genes in bacteria across the U.S. last year, according to a new CDC Vital Signs report.

These superbugs include those that cannot be killed by all or most antibiotics, are uncommon in a geographic area or the U.S. or have specific genes that allow them to spread their resistance to other germs.

One in four germs the CDC tested contained special genes that allow them to spread their resistance to other germs. When the CDC screened for superbugs, further investigation uncovered a hard-to-treat germ that spreads easily in one in ten people, even when they showed no symptoms. This means the germ could have spread undetected in the health care facility.

Rapid identification of the new or rare threats is the critical first step in CDC’s containment strategy to stop the spread of antibiotic resistance (AR). When a germ with unusual resistance is detected, facilities can quickly isolate patients and begin aggressive infection control and screening actions to discover, reduce and stop transmission to others.

“CDC’s study found several dangerous pathogens, hiding in plain sight, that can cause infections that are difficult or impossible to treat,” said CDC principal deputy director Anne Schuchat. “It’s reassuring to see that state and local experts, using our containment strategy, identified and stopped these resistant bacteria before they had the opportunity to spread.”